NAME

       aio_write - asynchronous write to a file (REALTIME)

SYNOPSIS

       #include <aio.h>

       int aio_write(struct aiocb *aiocbp);

DESCRIPTION

       The  aio_write()  function  shall write aiocbp->aio_nbytes to the file associated with aiocbp->aio_fildes
       from the buffer pointed to by aiocbp->aio_buf.  The function shall return when the write request has been
       initiated or, at a minimum, queued to the file or device.

       If prioritized I/O is supported for this file, then the asynchronous operation shall be  submitted  at  a
       priority equal to the scheduling priority of the process minus aiocbp->aio_reqprio.

       The  aiocbp argument may be used as an argument to aio_error() and aio_return() in order to determine the
       error status and return status, respectively, of the asynchronous operation while it is proceeding.

       The aiocbp argument points to an aiocb structure. If the buffer pointed  to  by  aiocbp->aio_buf  or  the
       control  block pointed to by aiocbp becomes an illegal address prior to asynchronous I/O completion, then
       the behavior is undefined.

       If O_APPEND is not set for the file descriptor aio_fildes, then the requested operation shall take  place
       at  the absolute position in the file as given by aio_offset, as if lseek() were called immediately prior
       to the operation with an offset equal to aio_offset and a whence equal to SEEK_SET. If  O_APPEND  is  set
       for  the  file  descriptor, write operations append to the file in the same order as the calls were made.
       After a successful call to enqueue an asynchronous I/O operation, the value of the file  offset  for  the
       file is unspecified.

       The aiocbp->aio_lio_opcode field shall be ignored by aio_write().

       Simultaneous asynchronous operations using the same aiocbp produce undefined results.

       If  synchronized  I/O  is  enabled  on  the file associated with aiocbp->aio_fildes, the behavior of this
       function shall be according to the  definitions  of  synchronized  I/O  data  integrity  completion,  and
       synchronized I/O file integrity completion.

       For  any  system action that changes the process memory space while an asynchronous I/O is outstanding to
       the address range being changed, the result of that action is undefined.

       For regular files, no data transfer shall occur past the offset maximum  established  in  the  open  file
       description associated with aiocbp->aio_fildes.

RETURN VALUE

       The  aio_write()  function  shall  return  the  value zero to the calling process if the I/O operation is
       successfully queued; otherwise, the function shall return the value -1 and  set  errno  to  indicate  the
       error.

ERRORS

       The aio_write() function shall fail if:

       EAGAIN The requested asynchronous I/O operation was not queued due to system resource limitations.

       Each of the following conditions may be detected synchronously at the time of the call to aio_write(), or
       asynchronously.   If  any  of  the  conditions below are detected synchronously, the aio_write() function
       shall return -1 and set errno to the corresponding value. If any of the  conditions  below  are  detected
       asynchronously,  the return status of the asynchronous operation shall be set to -1, and the error status
       of the asynchronous operation is set to the corresponding value.

       EBADF  The aiocbp->aio_fildes argument is not a valid file descriptor open for writing.

       EINVAL The file offset value implied by aiocbp->aio_offset would be invalid, aiocbp->aio_reqprio is not a
              valid value, or aiocbp->aio_nbytes is an invalid value.

       In the case that the aio_write() successfully  queues  the  I/O  operation,  the  return  status  of  the
       asynchronous  operation shall be one of the values normally returned by the write() function call. If the
       operation is successfully queued but is subsequently canceled or encounters an error,  the  error  status
       for  the  asynchronous operation contains one of the values normally set by the write() function call, or
       one of the following:

       EBADF  The aiocbp->aio_fildes argument is not a valid file descriptor open for writing.

       EINVAL The file offset value implied by aiocbp->aio_offset would be invalid.

       ECANCELED
              The requested I/O was canceled before the I/O completed due to an explicit aio_cancel() request.

       The following condition may be detected synchronously or asynchronously:

       EFBIG  The file is a regular file, aiobcp->aio_nbytes is greater than  0,  and  the  starting  offset  in
              aiobcp->aio_offset is at or beyond the offset maximum in the open file description associated with
              aiocbp->aio_fildes.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The aio_write() function is part of the Asynchronous Input and Output option and need not be available on
       all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       aio_cancel()  ,  aio_error()  ,  aio_read()  ,  aio_return()  ,  close()  ,  exec()  ,  exit() , fork() ,
       lio_listio() , lseek() , write() , the Base Definitions volume of IEEE Std 1003.1-2001, <aio.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
       Inc  and  The  Open Group. In the event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                                   2003                                          AIO_WRITE(P)